Along with the widespread use of large display devices such as liquid crystal televisions, higher-value-added products are required and thus development is being carried out. In particular, a technique to form a driver circuit, such as a scan line driver circuit, over the same substrate as a pixel area with the use of a thin film transistor (TFT) having a channel region of an amorphous semiconductor, specifically an oxide semiconductor, is under active development.
Examples of the structure of the driver circuit include a static shift register circuit which is disclosed in Patent Document 1 (see FIG. 2 and the like).
[Reference]
    [Patent Document 1] Japanese Published Patent Application No. S64-89810